Method of cathode disintegration



p 94 B. BERGHAUS ET AL 2,257,411

METHOD OF CATHODE DISINTEGRATION Filed Nov. 29, 1938 2 Sheets-Sheet 1 ep 1941- B. BERGHAUS ETAL 2,257,411

METHOD OF CATHODE DISINTEGRATION Filed Nov. 29, 1938 2 Sheets-Sheet 2 N5. Zerzhaus Patented Sept. 30, 1941 2,257,411 METHOD OF CATHODE DISINTEGRATION .Bernhard Berghaus, Berlin-Lankwitz, and Wilhelm Burkhardt, Berlinsaid Burkhardt assignor Application November 29 In Germany No 4 Claims.

The invention relates to a method of cathode disintegration wherein the output of the disintegration is made so high that the cathodes are heated to glow temperatures.

The invention refers more particularly to a method of cathode disintegration for the metallisation of articles by using plates and metal sheets, which method consists in this that the output of the disintegration is made so high that the plates or metal sheet cathodes reach glow temperatures. Preferably use is made of plate or metal sheet cathodes, the surface of which is greater than 50 square centimeters. The output of the disintegration that has to be applied thereto, in order to cause the plates to glow, diiiers according to the material to be disintegrated. The output of disintegration may reach up to 50 to 100 watts per square centimeter. Experiments have shown that plates or metal sheets of any desired dimensions disintegrate exactly the same amount per surface unit if the electrical load by the gas discharge is made to correspond to the load on sub-divided thin wire or band cathodes. As compared with the known sub-divided cathodes the present invention has the advantage that for the same size of cathode disintegrationchamber and for the same disintegration eflect per surface unit a much larger amount of cathode material can be accommodated. The thickness of the metal sheets 01'- plates to be disintegrated is entirely immaterial, so that with continuous operation a replacement of the cathode material in order to terminate the coating operation is not required, since it is possible to predetermine with sufficient reliability and to accommodate the amount to be disintegrated which is each time required for the coating operation. Moreover, by correspondingly increasing to a multiple the total amount to be disintegrated in the same time, the coating operation is reduced in the same proportion for the same metal deposition on the article to be coated. For instance, instead of 15 silver bands, each 1 millimeter wide and at distances of 30 millimeters from one another, there was disintegrated in a filling gas of 0.6 millimeter of mercury a silver plate 420 millimeters wide, corresponding to the width occupied by the one millimeter bands at a distance of 30 millimeters, at the same specific output which, as in the case of the'one millimeter bands, resulted in a glow temperature. The amount disintegrated was 26 times greater than that of the one millimeter bands in the same period, being approximately in the same relation as the surfaces of the bands to that of the plate.

discharge can take place in Grunewald, Germany; to said Berghaus .1938, Serial No. 243,013 vember 30, 1937 In addition to the proof that with corresponding load the disintegrated amount per square centimeter is not less favourable than in the case of sub-divided cathodes, it was surprisingly as-' certained that the current yield was increased, for instance, in the case of silver by about 100%. According to the present method all metals which can be worked up into plates or metal sheets can be disintegrated and be deposited on articles of any kind. 1

The invention will be more clearly understood by reference to the accompanying drawings wherein apparatus is disclosed for practicing the method.

In the drawings:

Fig. 1 shows a section through a cathode disintegration plant having a flat cathode of large surface, which can be loaded with 50 to watts per square centimeter, and

Fig. 2 is a side elevational view of the cathode metal sheet.

Fig. 3 is a part section through a cathode disintegration plant with a cathode of wires of large cross-section; and

Fig. 4 is an elevational view of the wires forming the cathode.

The cathode disintegration plant comprises a cathode disintegration chamber I, which can be evacuated by the vacuum pump 2 to the sub-atmospheric pressure required for the disintegration, and which may lie between 50 and 0.0001 and preferably between 5 and 0.01 millimeters of mercury. A small amount of filling gas, for instance hydrogen, can be introduced from the filling gas container 3 and through the valve 4 into the disintegration chamber. The material to be metallised, for instance two metal webs 5 and 6, is wound on two reels 1 and 8 and slides during the metallisation each over a cold surface 9 and I0 respectively, and after metallisation is wound on reels l I dium is supplied through the pipe I3 and is discharged through the pipe H.

The cathode metal sheet i5 to be disintegrated and which disintegrates towards both sides is secured by means of a holder IE to the current leadin I1, which is introduced into the disintegration chamber in an insulated and screened manner. The lead-in is hollow and a cooling medium may be introduced through the pipe i8 and be discharged through the pipe i9. The lead-in is screened by two metal sleeves 20 and 2|, which are spaced at such a short distance from the current lead-in and from one another that no glow the intermediate and i2 respectively. A cooling mespace. The insulating members 22 and I! serve for the purpose of insulating the screens, and N is a seal for instance a rubber seal. The assembly is clamped together by the clamping ring 25. 28 is a cooling chamber through which a cooling medium may be supplied through the pipe connection 21 and from which it is discharged by the pipe connection 2'.

The cathode i is fed with current from a source of direct or alternating current 29 over a switch 30 and an adjustable resistance ii, in the case of direct current the negative pole being connected to the current lead-in and the positive pole. for instance, to the wail of the chamber. According to the invention the metal sheet cathode is loaded with about to 60 watts per square centimeter of the cathode surface, whereby an exceedingly quick and favourable disintegration is obtained, so that a very adhering layer of considerable resistance and having a perfect metal structure is produced on the article to be coated.

The invention also relates to a method of cathode disintegration, more particularly for the inetallisation of articles while use is made of wire, band or profile cathodes, wherein wire or profile cathodes of large cross-section are used and are heated up to glow temperature by the output that is used for the disintegration. Wires or hands or profiles having a cross-section greater than 7 square millimeters, or wire diameters or profile dimensions of over 3 millimeters have been found to be especially favourable. Preferably the temperature is made as high as possible by regulating the output of the disintegration.

are thereby removed and the amount disintegrated as well as the current yield are moreover increased to a multiple in the same time. A large production, in disintegr ted material produces on the articles to be metallised a better structure of the layer provided thereon than is the case 31th slow metallisation by cathode disintegra- It has been ascertained that the amount disintegrated is independent of the cross-section dimensions of the shape of the cathode. For instance, exactly the same material per surface unit is disintegrated from wire cathodes having a diameter 15 times greater than in the case of the known thin wires, the electric total disintegration output being the same. However, it the cathode of a wire having a diameter 15 times greater is loaded corresponding to the proportion of the surface by the disintegration energy, so that the specific loading of the thin wire of for instance 0.3 millimeter diameter and that of the thick wire of for instance 4.5 millimeters diameter are the same, then th action is exactly the same as if 15 thin wires were simultaneously disintegrated. Moreover, in the case of the larger profile dimensions, a higher current yield is obtained, as will b seen from the following results.

Example Copper and silver wires of different thicknesses and 100 mm. long were disintegrated in hydrogen acting as a filling gas at 0.4 and 0.09 millimeter of mercury and by equal disintegration output In order to be able to load the thick wire or pro- 35 per square centimeter.

Disintegration Amount disinteoutput grated Current Dis 'r a: i yield Length Surface Total Specific in mm. in cm. in em. mm w/cm, mg./h. mgJhcm.

os'rnona MATERIAL on 0.3 l0 0.05 21 a2 0.0 0.03 275 3.0 10 a5 21 022 0.01 0.004 210 3.0 10 0.0 21 as 0.0 0.01 370 5.0 10 10 as m 0.4 0.00 000 oa'rnopn MATERIAL Ag 0. a 10 .0. cs 2.1 a 2 a 2 2. a 1540 3.0 10 9.0 2.1 an 2.0 0.21 1040 3.0 10 0.0 21 12 20.0 2.7 2000 0.0 10 10 as 2.2 30.2 24 2000 file cathodes up to the softening point and be- It follows from the table that, contrary to the yond, they are preferably provided with a core of a material fusing at a higher temperature. The transition from the solid to the liquid state increases considerably the speed of disintegration.

It has further been found that when a bead of molten material was formed at the lower end of a wire cathode, th disintegrated amount was increased up to three times, with other conditions being the same. The current yield was correspondingly increased three times. By using a core of, for instance tungsten wire, a cathode of copper of 5 millimeters diameter could be loaded up to the softening point, whereby the current yield was increased toover tour times.

According to the present method all the metals which can be formed into wire or profile cathodes can be disintegrated and be deposited on articles of any kind. The disadvantages of the very thin wires in a cathode disintegration plant opinion hitherto held, the profile dimension has no influence on the disintegrated amount per square centimeter of the surface of th cathode i! the specific output is comparatively kept constant, and in addition thereto the current yield in mg./amps. is substantially increased in the case of larger profile dimensions; for instance in the case of copper used as cathode material and a wire diameter of the cathode of 0.3 and 5.0 millimeters the specific load being the same an increase in the current yield by 40% was ascertained, and when silver was used as cathode material the increase was by In the cathode disintegration plant according to Figures 3 and 4 the reference numerals l to 14 and 1'7 to 31 refer to the same parts as in Figure The wire cathodes to be disintegrated Ila which are of large cross-section, for instance 30 square millimeters, which disintegrate towards both sides, are securedby means of a holder lid to the current lead-in II, which is introduced into the disintegration chamber in an insulated and screened manner. The cathode la is fed from the source 29 ofdirect or alternating current over a switch 30 and an adjustable resistance 3|; in the case of direct current the negative pole is connected to the current lead-in and the positive pole, for instance to the wall of the chamber. According to the invention the cathode wires are loaded with about 20' to 60 watts per square centimeter of surface, whereby an exceedingly quick and favourable disintegration is obtained, so that a very adhering and very resistant layer which has a perfect metallic structure is produced on the article to be coated.

What we claim is:

1. The method of coating material by cathode disintegration wherein the cathode hasa surface area greater than 50 square centimeters which comprises, placing the material to be coated within a sealed conductive housing, filling the housing with hydrogen gas and adjusting the pressure within the housing to support cathode disintegration therein, impressing a voltage across the cathode and the housing to disintegrate particles from the surface of the cathode onto the material to be coated, and maintaining said voltage at such a value that the electrical energy providing the disintegration heats the cathode to such a temperature that the surface of the cathode starts to fuse.

2. The method of coating material by cathode disintegration wherein the cathode is formed of sheet metal having a surface area greater than 50 square centimeters which comprises, supporting material to be coated within a sealed conductive housing adjacent one face of the cathode, supporting additional material within the housing adjacent the other face of the cathode, filling the housing with hydrogen and adjusting the pressure of hydrogen gas within the housing between 50 and 0.001 millimeters of mercury so as to support cathode disintegration therein, impressing a voltage across the cathode and the housing to disintegrate particles simultaneously from both surfaces of the cathode onto the material to be coated, and maintaining the voltage at such a value that the electrical energy providing the disintegration heats the cathode to such a temperature that the surface of the cathode melts during the disintegration thereof.

3. A method of coating material by cathode disintegration wherein the cathode has a surface area greater than 50 square centimeters which comprises, placing the material to be coated within a sealed conductive housing, filling the housing with hydrogen gas and adjusting the pressure within the housing to support cathode disintegration therein, impressing a voltage across the cathode and the housing to disintegrate particles from the cathode onto the material to be coated, and adjusting and maintaining said voltage at such a value that the electrical energy providing the disintegration heats the cathode to such a temperature that the surface of the cathode becomes molten during disintegration thereof.

4. The method of coating material by cathode disintegration wherein the cathode has a. surface area greater than 50 square centimeters which comprises, placing the material to be coated within a sealed housing, filling the housing with gas hydrogen and adjusting the pressure thereof within the housing to support cathode disintegration therein, creating an electrical glow discharge within the housing to disintegrate particles from the surface of the cathode onto the material to be coated, and adjusting and maintaining the electrical discharge energy at such a value as to heat the cathode to such a temperature that the surface of the cathode melts during disintegration thereof.

BERNHARD BERGHAUS. WILHELM BURKHARDT. 

